// 设置响应头的中间件
module.exports = async (ctx, next) => {
  const contentType = 'application/json, charset=utf-8'
  ctx.set('Content-Type', contentType)
  // 解决跨域问题
  ctx.set('Access-Control-Allow-Origin', '*')
  ctx.set('Access-Control-Allow-Methods', 'OPTIONS,GTE,POST,DELETE,PUT')
  await next()
}